We propose to examine well, term infants using noninvasive measurements of carbon monoxide in breath as an index of bilirubin production. From these data we will formulate criteria to identify neonates who are at low risk for developing significant jaundice. The application of the risk criteria to well, term neonates will permit a clinician to safely reduce the duration of postnatal hospitalization for most infants without the need for close supervision of bilirubin levels, as well as target other infants with short hospital stays.